BYU Cleanroom - PECVD 1

Plasma Enhanced Chemical Vapor Deposition (PECVD) 1 Machine

Contact Information:
   Faculty Contact:    Aaron Hawkins
   Staff Contact:    Don Dawson
   Student Contact:   Evan Lunt

Maintenance Request for PECVD 1

SCHEDULER IS REQUIRED

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General Description
1. The Plasma Enhanced Chemical Vapor Deposition (PECVD) machine is used to deposit thin dielectric films. It combines up to four gases at pressures between 0.1 and 1 Torr and uses an RF source of up to 200 Watts to ionize the resultant gas mixture, causing film deposition on a heated substrate.
  
  Films deposited with the system include: SiO₂, SiO_xN_y, and Si₃N₄.
Operating Instructions
1. Turning on the necessary equipment
  1. The process gases include 5% silane in helium (SiH₄/He), ammonia (NH₃), nitrous oxide (N₂O), and halocarbon cleaning gas (CF₄/O₂ blend). The tanks are located in the gas cabinet adjacent to the cleanroom. To turn on the 5% silane and ammonia, twist the red shutoff button on the control panel for each gas clockwise until it pops up, then press the ‘start’ button. The CF₄ and the nitrous oxide are not run through the control panel of the gas cabinet. The CF₄ must be turned on and off using the valve on top of the cylinder next to the cabinet. The nitrous oxide does not need to be turned on, just check the gauges above those for the CF₄ to make sure there is at least 15-20 psi.
  2. The vacuum pump for the PECVD is located in the back room (there is a label indicating the machine - the second machine on the right when you enter the back room). It can be switched on and off using the switch box mounted behind the Anelva RIE, which is to the right of the PECVD.
  3. The chiller located on the floor next to the PECVD must be turned on anytime the substrate heater is on. It can be switched on with the on/off button on the front panel. Verify that water is flowing by looking at the flow meters on the front panel. The chiller should not be turned off before the plate has cooled to 100°C.
2. Manual Run
  1. Push "TAB" to move the cursor, "+" turns an option ON, "-" turns an option OFF. When in a field with numbers, use the arrows to switch positions in the number and the number pad to set the numbers.
  2. Manual Screens
    1. Screen 1: Oxide 6000ANG MANUAL
      
      Power: OFF Watts 100
      
      Pressure: 0.000 Torr
      
      Vacuum: OFF Vent: OFF
    2. Screen 2: Oxide 6000ANG MANUAL
      
      GAS1: OFF MFC1: 16.0% (NH₃)
      
      GAS2: OFF MFC2: 70.0% (SiH₄)
      
      GAS3: OFF MFC3: 25% (N₂O)
    3. Screen 3: Oxide 6000ANG MANUAL
      
      GAS4: OFF MFC4: 10.0% (CF₄)
      
      Htr: 250°C Temp: 000°C Don't worry about these last two lines
      
      Bias: ----- Volts
  3. How to get back to the Manual Run screen if the machine gets turned off:
    1. 1. Turn on the power or pull out the emergency kill switch.
    2. 2. The first screen you see should look like this:
      Oxide 6000ANG (01)
      
      Select Recipe
      
      Review Recipe
      
      Configure System
    3. 3. Push "ENTER" on the first line, "Oxide 6000ANG (01)".
    4. 4. Push "TAB" once to "MANUAL RUN", then push "ENTER".
    5. 5. You should see the familiar Manual Run Screen 1.
    6. 6. Be sure to reset the correct gas flows for your recipe!
  4. Starting a process
    1. 1. Turn on vacuum to 0.000 Torr, leaving vent on for 5-10 seconds to purge the chamber of oxygen.
    2. 2. Wait for it to pump down and temperature to come up (about 1 minute usually).
    3. 3. Turn on process gases.
    4. 4. Wait 5-10 seconds, then turn on vacuum to process pressure.
    5. 5. Turn on power and start timer.
  5. Stopping a process
    1. 1. Turn off power.
    2. 2. Turn off process gases.
    3. 3. Set pressure to 0.000 Torr, wait about 1 minute.
    4. 4. Vent and purge process gases.
      1. Turn on vent for 1-2 seconds at a time, twice.
      2. In between, wait 30-60 seconds to pump down.
    5. 5. Turn on vent, then turn off vacuum.
3. Shutting off the PECVD
  1. After cleaning out the chamber, set the pressure to 0.000 Torr and turn on the vacuum for about 3 minutes.
  2. Make sure the gases and the PECVD pump are turned off in the back. If you are the last one to leave the cleanroom at night, shut off the house vacuum and the nitrogen as well.
  3. The chiller next to the PECVD can be switched off when the PECVD has cooled down to at least 100°C.
  4. Don't forget to sign the log book!
Cleaning Instructions
1. Things to remember:
  1. NO WATER ALLOWED - do not spray water anywhere inside the chamber. The only approved use of DI water is using moistened cleanroom wipes to wipe down the inside of the chamber to loosen the film residue.
  2. Do not touch the hot plate with your gloves, the vacuum, or anything else when it is hot. In addition to being a safety hazard, you will contaminate the plate with carbon residue that will affect subsequent growth. If this happens, perform a CF₄ clean until the residue is gone.
  3. No hard scrubbing of the hot plate. Applying pressure to the hot plate will push the thermocouple out of contact with the hot plate, causing erroneous temperature readings.
  4. Clean the outside of the machine. Wipe and blow down the outside of the chamber.
2. Simple Chamber Clean - use when there is visible powdery residue.
  1. Vacuum the chamber lid including the showerhead. Pay special attention to the screws in the showerhead as well as the groove around the showerhead. This should remove most of the particulate matter. Vacuum around the bottom plate (but NOT the heated center plate if it is hot). Be careful not to touch the hot plate with the vacuum hose or your gloves.
  2. Use cleanroom wipes moistened with isopropyl alcohol to wipe down the chamber lid and walls. Again, pay special attention to the showerhead and the groove at the base of the showerhead. Also, wipe out the window at the top of the chamber. Wipe the base plate and the center plate if it is not hot.
  3. Use the nitrogen gun to blow out any remaining particles from the showerhead groove and the hot plate. If you did the previous steps properly, you shouldn't see any particles flying around. If you do, stop and go back to step 2.
  4. Use a cleanroom wipe moistened with isopropyl alcohol to wipe off the O-ring on the chamber lid.
  5. Close the lid and use cleanroom wipes and the nitrogen gun to clean off the outer surfaces of the PECVD. There should not be any visible dust anywhere on the machine. Pay attention to the controller.
3. CF₄ Clean - must be done every 4 microns of deposited film to clean the hot plate.
  1. Perform a simple chamber clean as described above.
  2. Run a CF₄ process for at least 45 minutes or until there is no residue on the hot plate.
4. Full Chamber Clean - as necessary.
  1. Vacuum the chamber lid including the showerhead. Pay special attention to the screws in the showerhead as well as the groove around the showerhead. This should remove most of the particulate matter. Vacuum around the bottom plate (but NOT the heated center plate if it is hot). Be careful not to touch the hot plate with the vacuum hose or your gloves.
  2. Use cleanroom wipes moistened with DI water to wipe down the chamber lid and walls. This will loosen the deposited film and make removal easier. DO NOT spray water ANYWHERE inside the machine! Your PECVD privileges will be suspended if you do this. Do not use water to clean the hot plate or the base plate.
  3. Use Scotchbrite pads to remove the film from the showerhead and chamber walls. Do not scrub the hot plate except VERY gently - you will mess up the thermocouple if you press down on the hot plate. Focus on removing the film from the showerhead and chamber walls - use a CF4 clean cycle to clean the hot plate. Do not use Scotchbrite on the chamber window - it is already scratched enough.
  4. Repeat steps 2 and 3 as necessary, using the vacuum to remove powder as it builds up. When done, pass the vacuum over the entire surface of the showerhead to remove particles from the small holes. Do the same with the groove at the base of the showerhead. There should be no visible particles left after this step.
  5. Use cleanroom wipes moistened with isopropyl alcohol to wipe down the chamber lid and walls. Again, pay special attention to the showerhead and the groove at the base of the showerhead. Also, wipe out the window at the top of the chamber.
  6. Use the nitrogen gun to blow out any remaining particles from the showerhead groove and the hot plate. If you did the previous steps properly, you shouldn't see any particles flying around.
  7. Use a cleanroom wipe moistened with isopropyl alcohol to wipe off the O-ring on the chamber lid.
  8. Close the lid and use cleanroom wipes and the nitrogen gun to clean off the outer surfaces of the PECVD. There should not be any visible dust anywhere on the machine. Pay attention to the controller.
  9. Perform a CF₄ Clean as described above for at least 45 minutes.
Process Recipes